Axle drive unit, in particular an electrical drive unit for driving a wheel axle of the transaxle type

ABSTRACT

The invention relates to a shaft drive unit ( 1 ), in particular an electrical drive unit for driving a wheel shaft for use in vehicles; having an electrical machine comprising a rotor and a stator; having a transmission unit, comprising at least one input which can be connected in a rotationally fixed manner to the rotor of the electrical machine, and at least one output which can be connected in a rotationally fixed manner to the wheel shaft. The electrical machine, the input and the output of the transmission unit and the wheel shaft are arranged coaxially with respect to one another. The electrical machine has at least one associated converter unit ( 11 ) and one associated braking resistor unit. The invention is distinguished in that the converter unit ( 11 ) forms a physical unit with the electrical machine.  
     The braking resistor unit is arranged in the immediate physical vicinity of the electrical machine and around the circumference of the input or output drive shaft of the electrical machine or of the wheel shaft.

[0001] The invention relates to a shaft drive unit, in particular anelectrical drive unit for driving a wheel shaft with a transverse shaftstructure, in detail having the features from the preamble of claim 1.

[0002] A large number of embodiments are known for the designconfiguration and construction of electrical drives for vehicles, inparticular hybrid drives for vehicles. Embodiments for driving a frontwheel shaft of a vehicle are in this case preferably designed using atransverse shaft structure. The shaft drive unit in this case comprisesan electrical drive machine which can be operated as an electric motorin the traction mode and is connected to the wheel shaft via atransmission unit. The power for operating the electrical drive machineis provided via a power supply system which, depending on the choice ofenergy source, may have various configurations. It is in this casefeasible for the power source to be in the form of an internalcombustion engine, an energy storage unit or what is referred to as afuel cell. In each case, means are required for transmitting the powerto the electrical drive machine. In order to control the electricaldrive machine, it has at least one converter unit associated with it,which converter units determine the magnitude of the torque and rotationspeed which can be delivered from the rotor of the electrical drivemachine.

[0003] In embodiments with a transverse shaft structure, the rotor ofthe electrical drive machine is connected in a rotationally fixed mannerto an input (when considered in the power flow direction in the tractionmode) of the transmission unit. The output from the transmission unit iscoupled in a rotationally fixed manner to the wheel shaft.

[0004] The expression wheel shaft in this case relates to the couplingto the wheels, which are connected in a rotationally fixed manner tothat shaft, so that there is no relative movement between the wheels andthe wheel shaft. However, with regard to power transmission, the wheelshaft acts as an input drive shaft for the wheels, which are coupled ina rotationally fixed manner to it. However, the expression wheel shaftis used in the following text. The input drive to and the output drivefrom the transmission unit as well as the rotor of the electrical drivemachine and the wheel shaft are arranged coaxially with respect to oneanother. Specifically, this means that, for example, the rotor of theelectrical machine and the input to drive to the transmission unitenclose the wheel shaft.

[0005] At least one converter unit is provided in order to drive theelectrical machine, and can be arranged at any desired distance from theelectrical machine, within the vehicle. The coupling is in this caseprovided via appropriately shielded electrical cables. In order toensure reliable operation, cooling water lines must then also beprovided, in addition to the electrical cables, between the converterunits, in order to provide a separate cooling circuit. Owing to thephysical separation, the line and cable routing required for thispurpose is generally also very expensive and complicated. Furthermore,long cable runs also mean an increase in the frequency-dependent effectsof electrical, magnetic or electromagnetic fields on the environment, inparticular on living beings and technical systems. This effect, whichcan be summarized by the expression electromagnetic compatibility, isdefined by numerous national and international standards. Appropriateshielding must be provided in order to comply with the limit valuesspecified in this case. However, this is independent of the line andcable routing and may differ to a very major extent from one particularapplication to another, in which case the EMC shielding must beimplemented as an additional feature, with different boundaryconditions, for each application. A further major disadvantage of theseembodiments is that the reliability of the overall system decreases asthe length of the cooling water lines and/or the electrical connectingcables increases, and this is due, inter alia, to the larger area onwhich insulation damage can occur on electrical cables, and over whichleakages can occur in the cooling circuit.

[0006] By analogy, this statement also applies to the association ofbraking resistor units with the electrical drive machine, with thesebraking resistor units converting the electrical power to thermal energyin the generator mode. In this case as well, there is a requirement forthese braking resistor units to be integrated in the drive system in anoptimum manner. Since they are electrically coupled to the electricalmachine, the same problems as those which occur in the arrangement ofthe converter units exist in embodiments where considerable physicaldistances are involved.

[0007] The invention is thus based on the object of further developingan embodiment of a shaft drive unit, in particular of an electricaldrive unit, for driving wheel shafts of a vehicle in such a manner as toachieve optimum utilization of physical space by the components whichcan be associated with the electrical drive machine, while at the sametime ensuring freedom from disturbance with regard to the othercomponents required for the method of operation of the vehicle. In thiscase, these additional components are intended to be arranged in asimple manner, and to be as independent as possible with regard to theconfiguration of the vehicle. The cable connections required forelectrical coupling between the electrical machine and the brakingresistor unit, and between the electrical machine and the converterunit, are intended to be reduce to a minimum and, furthermore, the[lacuna] for a cooling system for cooling the cables and fortransporting the heat produced in the braking resistor unit to be keptas low as possible.

[0008] The solution according to the invention is characterized by thefeatures of claim 1. Advantageous refinements are specified in thedependent claims.

[0009] The shaft drive unit, in particular the electrical drive unit fordriving a wheel shaft of a vehicle, comprises at least one electricaldrive machine with at least one rotor and one stator, and a transmissionunit which is connected between the electrical drive machine and thewheel shaft, when considered in the power flow direction in the tractionmode. The rotor of the electrical drive machine is connected at leastindirectly in a rotationally fixed manner to an input of thetransmission unit, which is also referred to as an input drive, that isto say it is coupled either directly or with the interposition offurther power-transmitting elements. One output of the transmissionunit, which is also referred to as the output drive, is connected atleast indirectly in a rotationally fixed manner to the wheel shaft. Thismeans that the rotationally fixed connection is produced either directlyfrom the output drive from the transmission unit to the wheel shaft, orelse with the interposition of further power transmitting elements. Therotor of the electrical machine, the input drive to the transmissionunit, the output drive from the transmission unit and the wheel shaftare arranged coaxially with respect to one another. In order to drivethe electrical machine, it has at least one associated converter unit.The electrical machine has an associated braking resistor unit, in orderto convert the electrical energy produced in it during generatoroperation into thermal energy. According to the invention, theelectrical drive machine forms a physical unit with the converter unit,while the braking resistor unit is arranged around the input or outputdrive shaft of the electrical machine or the wheel shaft, in particularits circumference. The definition input or output drive shaft in thiscase always relates to the direction of the power flow in the motor andgenerator mode of the electrical machine. This expression in this casedoes not necessarily cover only elements in the form of shaft ends, butalso includes the rotating elements which can carry out the function ofthe input or output drive shaft.

[0010] The solution according to the invention allows a shaft drive unitto be provided which is configured for optimum utilization especiallywith regard to the available physical space. The available physicalspace, which need not be made available for other power-transmittingelements, is generally utilized in this case. This solution makes itpossible to integrate at least one braking resistor unit in the drivetrain in the vehicle with as little complexity as possible, irrespectiveof the given installation conditions, in an area which is generally notused. In this area between the wheel shaft and the electrical machine,which acts as a drive motor in the traction mode, there is also no needto be concerned about obstructions to the operation of other elementsrelating to the implementation of the functionality of the vehicle. Theconnection lines required for electrical coupling can in this case bekept very short. The EMC shielding can be implemented jointly for theentire unit comprising the electrical machine, which acts as the drivemotor in the traction mode, and the braking resistor unit. This alsoapplies to the additional integration of the converter unit in theelectrical machine. Furthermore, it is possible to produce the totalityof the electrical machine, which acts as a drive motor in the tractionmode, together with the braking resistor unit and the converter unit asa prefabricated unit, and to offer them in this form. Integration indrive systems is thus cost-effectively possible in a very simple mannerirrespective of the options for attachment of these additionalfunctional elements to the vehicle frame or other elements.

[0011] The arrangement options or integration options for the converterunit and braking resistor unit will be considered separately, in theirown right, in the following text. The braking resistor unit is arrangedon the housing of the electrical machine, which acts as a drive motor.There are a wide range of options for the coupling to the housing. Thisis preferably done mechanically by flange-connection of the brakingresistor unit to the housing. However, it is also feasible if theelectrical coupling option between the braking resistor unit and theelectric motor is configured appropriately, for example in the form ofan electrical plug connection, to use these means for attachment aswell. However, in this case it necessary for the electrical machine tobe configured appropriately with respect to the means for electricalcoupling.

[0012] Each electrical machine which acts as a drive motor has eitherone or more associated braking resistor units. Depending on the designconfiguration of the braking resistor unit, this unit is, in oneembodiment, arranged grouped with a number of braking resistor units inan annular shape around the input or output drive shaft of theelectrical machine which acts as a drive motor or, alternatively, theyare arranged alongside one another in the axial direction, when viewedwith the drive system in the installed position.

[0013] One advantage of the former case is that, in terms of theirgeometrical configuration, conventionally designed braking resistorunits can be integrated individually or jointly in the drive train inthe manner according to the invention.

[0014] However, it is preferable to choose a configuration for theelectrical braking resistor unit which is suitable for at leastpartially enclosing the input or output drive shaft, with an annularconfiguration of the braking resistor unit preferably being desirable.The braking resistor unit can then be arranged coaxially with respect tothe input or output drive shaft of the electrical machine which acts asa drive motor. This arrangement option represents the best variant withregard to provision of the connecting elements and the required physicalspace.

[0015] For the situation where a number of braking resistor units arerequired, these are likewise preferably configured in an annular shapeand are of modular construction such that, when viewed in the installedposition, they are arranged alongside one another in the axial directionand coaxially with respect to the input or output drive shaft of theelectrical machine, which acts as a drive motor. The individual resistorunits are most easily coupled to one another in this case viainterlocking and force-fitting connections.

[0016] In the annular configuration of the braking resistor unit, it isnecessary to ensure that the internal diameter of the braking resistorunit is designed such that it is possible for it to enclose the input oroutput drive shaft of the electrical machine, which acts as a drivemotor. Depending on the dimensions in the axial direction, that is tosay the extent of the braking resistor unit away from the housing wallof the electrical machine, it is possible for the braking resistor unitto enclose not only the input or output drive shaft of the electricalmachine which acts as a drive motor, but also the coupling to the shafttrain which may be connected to it, or to some other transmissionelement. The coupling between the input or output drive shaft of theelectrical machine and the shaft train or some other element for powertransmission, for example a rotation speed/torque conversion ortransmission device, can be designed in a wide range of ways. In thesimplest case, both

[0017] the shaft train or rotation speed/torque conversion ortransmission device, in particular their connecting shaft, and the inputor output drive shaft of the electrical machine

[0018] each have a flange-like end region, in which case the twoflange-like end regions can be coupled to one another with an interlockand/or force fit. However, configurations with coupling or clutchdevices are also feasible.

[0019] The solution according to the invention for drive systems with atleast one electrical machine which can be operated as a motor andgenerator and can be coupled via a shaft train at least indirectly to atleast one wheel which can be driven can be used, irrespective of thenature of the power supply which is used in the traction mode anddetermines the nature of the drive system. Integration is thus possiblein

[0020] a) diesel-electric drive systems,

[0021] b) drive systems with a fuel cell drive,

[0022] c) drive systems with an external electrical power supply, forexample from an overhead line.

[0023] In the first-mentioned case, an internal combustion engine actsas an energy source and can be mechanically coupled to an electricalmachine which can be operated as a generator in the traction mode. Theelectrical machine which can be operated as a generator can beelectrically coupled to the electrical machine which acts as a drivemotor. The electrical coupling is provided via a voltage intermediatecircuit. The electrical machine which can be operated as a generator andthe electrical machine which acts as a drive motor in the traction modehave associated devices (which are appropriate for controlling theelectrical power which can be produced or consumed) in the form ofconverters, which may be controllable.

[0024] In the case of the second option, mentioned at b) chemical energyis converted to electrical energy via a fuel cell unit, and can be usedfor supplying the electrical machine which acts as a drive motor.

[0025] In the case of the energy source mentioned at c) electrical poweris provided from an external network, which is used for supplying theelectrical machine which acts as a drive motor.

[0026] There are a wide range of options for the specific designimplementation of the overall drive system, and these are within theabilities of a responsible person skilled in the art, in accordance withthe operational requirements.

[0027] The combination of the electrical machine and converter unit toform a physical unit may likewise be carried out in a different way. Inthis context, the expression physical unit means a combination of theelectrical machine and of the converter unit which is associated withit, and is distinguished in that, from the physical point of view, thereis no physical separation, that is to say the converter unit is arrangedin the region of the electrical machine, in particular in its housing,and touches it, irrespective of the connecting cables which may berequired for the electrical coupling. The components associated with theconverter unit are generally combined in one housing. An electricalcoupling to the electrical machine can be provided via appropriateconnections. For this purpose, the converter unit has appropriate meanspreferably in the form of screw connections. A physical unit may beformed from an electrical machine and an associated converter unit invarious ways. The essential feature is that there is always anelectrical coupling. In addition, it is possible to connect theconverter unit mechanically to the electrical machine. The followingvariants are feasible for providing the coupling:

[0028] interlocking,

[0029] force-fitting,

[0030] integral material connection.

[0031] The specific embodiment may include a combination of thesecoupling options. In the simplest case the mechanical coupling betweenthe converter unit and the electrical machine associated with it isprovided via the means for electrical coupling. In this case, the meansfor mechanical coupling are formed together with the means forelectrical coupling by the same component, or the same components. Thismeans, for example, that the provision of an electrical screw connectionat the same time allows mechanical coupling between the electricalmachine and the converter unit associated with it. In this case, thecorresponding arrangement of the converter unit and the configuration ofthe electrical coupling allow the converter unit to be supported on theelectrical machine.

[0032] Furthermore, it is possible to associate the means for electricalcoupling and the means for providing the mechanical coupling withdifferent components. In the simplest case, the mechanical coupling isfor this purpose provided via means which allow coupling between thehousing of the converter unit and the housing or some other supportingelement for the electrical machine. These may be interlocking,force-fitting and/or formed by an integral material connection. Thisoffers the advantage of a fixed association between the converter unitand the electrical machine, in which case the entire unit comprising theelectrical machine and converter unit can be offered preassembled as amodule, and in a form which can be handled on its own.

[0033] A detachable connection is preferably used. This offers theadvantage of simple replacement in the event of defects and/or whenadaptation is desired to other boundary conditions which require the useof a different type of converter unit.

[0034] The converter units themselves can in this case be in the form ofinverter units of different types. In the simplest case, a converterunit comprises at least one diode rectifier device. This may in turnhave arms in which a number of diodes are connected in parallel and/orin series. In this case, diodes of the same type are preferably used.Reference should be made to the known relevant specialist literature forfurther options relating to the configurations of converter units, inparticular inverter units.

[0035] Depending on the configuration of the electrical machine, theembodiment and the number of braking resistor units, there are variousoptions for the specific arrangement of the converter unit and of thebraking resistor units on the electrical machine. If the brakingresistor units are arranged eccentrically on one of the end surfaces ofthe electrical machine, it is feasible for the converter unit likewiseto be integrated in the area of this end surface such that the converterunit is likewise provided on the circumference of the wheel shaft or theinput or output drive shaft of the electrical machine. Otherwise, it ispossible, depending on the coupling and arrangement of the electricalmachine and transmission unit with respect to one another, to integratethe converter unit, or the combination of the electrical machine andconverter unit, at any desired point in the region of the externalcircumference. In the case of configurations with a transverse shaftconstruction, the transmission unit and the electrical machine arepreferably arranged physically immediately adjacent to one another. Inthis case, the housings of the two units—the transmission unit and theelectrical machine—are preferably flange-connected to one another. Inthis case, at least the braking resistor unit is arranged on that endsurface of the electrical machine which faces away from the transmissionunit. If sufficient physical space is still available, the converterunit is likewise arranged either on the end surface or on thecircumference of the electrical machine. However, if it is arranged onthe circumference, an embodiment is chosen which, in the installedposition, is characterized in that the converter unit is arranged infront of or behind the electrical machine, in a side view of thevehicle.

[0036] The solution according to the invention will be explained in thefollowing text with reference to figures in which, in detail:

[0037]FIG. 1 shows, in a simplified form using a section illustration,one preferred embodiment of a shaft drive designed according to theinvention; and

[0038]FIGS. 2a and 2 b show alternative embodiment and arrangementoptions, compared to one another, for braking resistor units.

[0039]FIG. 1 uses an axial section to show the basic design of a shaftdrive unit 1 designed according to the invention, in particular in theform of an electrical drive unit 2 for driving a wheel shaft 3 with atransverse shaft structure. The shaft drive unit 1 comprises at leastone electrical machine 4, which acts as a drive motor in the tractionmode, in particular an electric motor and a transmission unit 5 coupledto it. The transmission unit 5 is in this case arranged between theelectrical machine 4 and the wheel shaft 3 which is to be driven. Theexpression wheel shaft is in this case chosen with respect to the wheelssince the wheel shaft can be coupled in a rotationally fixed manner tothe wheels, that is to say there is no relative movement between thewheel and the shaft. However, with respect to its operation, this actsas an input drive shaft. The electrical machine 4 has at least one rotor6 and one stator 7, with the rotor 6 being connected in a rotationallyfixed manner to an input 8 of the transmission unit 5, when viewed inthe power flow direction in the traction mode. This input 8 acts as aninput drive for the transmission unit 5, when viewed in the power flowdirection in the traction mode.

[0040] The electrical machine 4 is preferably in the form of atransverse flux machine. This allows a high power density with a smallphysical height, and is thus optimally suitable for use in a motorvehicle. The transmission unit 5 furthermore has at least one output 9which, when viewed in the power flow direction in the traction mode,acts as an output drive from the transmission unit 5 and is connected atleast indirectly in a rotationally fixed manner to the wheel shaft 3. Indetail, this means that the output 9, that is to say the output drivefrom the transmission unit 5, is either connected directly in arotationally fixed manner to the wheel shaft 3, or else further powertransmission elements are connected inbetween. In the illustrated case,the transmission unit 5 has a differential 25, which is coupled to oneoutput 24 of the epicyclic gear stage 23, in addition to the epicyclicgear stage 23 itself. The input 8 of the transmission unit 5 is in thiscase formed by the sun wheel 23.1 of the epicyclic gear stage 23. Theweb 23.2 acts as an output 24, and is connected to an input 27 of thedifferential 25. The differential 25 has two outputs 26.1 and 26.2,which at the same time form the outputs 9.1 and 9.2 of the transmissionunit 5, and are coupled in a rotationally fixed manner to the wheelshaft, in particular to the individual wheel shaft parts 3.1 and 3.2,which are each connected in a rotationally fixed manner to one wheel.

[0041] In the case of the transverse shaft structure, at least the rotor6 of the electrical machine 4—the input drive 8 of the transmission unit5, the output drive or drives 9.1 and 9.2 of the transmission unit 5 andthe wheel shaft 3 or the wheel shaft parts 3.1 and 3.2—are arrangedcoaxially with respect to one another. The transmission unit 5 ispreferably arranged coaxially with respect to the wheel shaft 3.However, configurations are also feasible in which the transmission unithas a design which is substantially asymmetric with respect to the wheelshaft 3.

[0042] In order to convert the electrical power (which has a “braking”function over at least a part of the operating range) produced in thegenerator mode by the electrical machine 4, which acts as a wheel drivemotor in the traction mode, into thermal energy for differentapplications, the electrical machine 4 has at least one associatedbraking resistor unit 10. This braking resistor unit 10 is arranged onthe electrical machine 4, and is preferably designed such that it can beflange-connected to it. Furthermore, the electrical drive machine 4 hasat least one associated converter unit 11 for drive purposes, inparticular in order to influence the rotation speed/torque conversion.In addition, according to the invention, the converter unit 11 is eitherarranged directly on the electrical machine 4 or is integrated in it,and hence, together with this electrical machine, forms a physical unit20.

[0043] In the illustrated embodiment, the braking resistor unit 10 onthe housing 12 of the electrical machine 4 is arranged on that end face13 of the housing 12 which faces away from the transmission unit 5. Inthis case, the arrangement in the radial direction is produced withrespect to the rotation axis RE of the electrical machine 4, preferablyin a region between the rotation axis RE and the external circumference14 of the housing 12 of the electrical machine. An extent considerablybeyond the external circumference 14 in the radial direction is likewisefeasible. However, it is preferable to aim for configurations which donot, or do not significantly, go beyond the region defined in the heightdirection by the dimensions of the electrical machine and thetransmission unit 5. The braking resistor unit 10 is in this casearranged around the circumference of the input drive or output driveshaft 28 of the electrical machine 4 or of the wheel shaft 3. In thisembodiment, physical space which exists in any case but cannot be usedfor other power-transmitting elements is used in an ideal manner foraccommodation of power elements. The braking resistor unit 10 can beelectrically coupled to the electrical machine 4. The definition of theinput or output drive shaft of the electrical machine 4 is in this casealways considered in the direction of the power flow in the motor andgenerator mode. This expression does not in this case necessarily meanonly elements in the form of shaft ends, but also rotating elementswhich can carry out the function of the input or output drives. Thissolution, in conjunction with a drive unit with a transverse shaftstructure, allows the braking resistor unit 10 to be integrated withlittle complexity and independently of the given installation conditionsin the vehicle, in an area of the drive train which previously had nopurpose whatsoever. In this area between the electrical machine 4, whichacts as a wheel-drive motor, and the wheel shaft, there is also no needto be concerned about any obstructions to the operation of otherelements for providing the functionality of the vehicle. The cableconnection or cable connections required for electrical coupling can bekept very short. The EMC shielding can be provided jointly for theentire unit comprising the electrical machine 4, which acts as a drivemotor in the traction mode, and the braking resistor unit 10.

[0044] There are a large number of options for the coupling to thehousing 12. This is preferably done mechanically by flange-connection ofthe braking resistor unit 10 to the housing 12. However, it is alsofeasible, if the electrical coupling option between the braking resistorunit 10 and the electrical machine 4 is configured appropriately, forexample in the form of an electrical plug connection, to use these meansfor attachment as well. This is dependent on the electrical machine 4,which acts as a drive motor, being configured in an appropriate mannerwith respect to the means for electrical coupling.

[0045] Each electrical machine 4 which acts as a drive motor has atleast one associated braking resistor unit, and preferably a number ofsuch braking resistor units 10.1 to 10 .n. Depending on the designconfiguration of the braking resistor unit 10 or units 10.1 to 10 .n, itor they are arranged, in one embodiment, with a number of brakingresistor units 10.1 to 10 .n either in an annular shape one behind theother around the circumference of the wheel shaft 3 as shown in FIG. 2a,or else in each case around the circumference of the wheel shaft, viewedin the axial direction when the shaft drive unit 1 is in the installedposition, but arranged alongside one another. This embodiment is shownin a view from the side according to FIG. 1 in FIG. 2b, but illustratedin a considerably simplified form. The individual resistor units 10.1 to10 .n are in this case preferably combined to form a physical unit 15,which is flange-connected to the end surface 13 of the electricalmachine 4. In this case, they are attached by means of interlockingand/or force-fitting connections. The individual braking resistor units10.1 to 10 .n are preferably designed identically in terms of theirdesign configuration and dimensions. Their dimensions in the radialdirection are preferably designed such that they do not extend beyond asize which corresponds to the size of the external circumference 15 ofthe electrical machine 4. The radial extent is preferably in the regionbetween the external circumference 16 of the wheel shaft, or of a part17 of the housing 12 of the electrical machine 4 which loops around it,and the external circumference 14 of the electrical machine 4. In boththe embodiments illustrated in FIGS. 2a and 2 b, the end surface 13 ofthe housing 12 is free of the arrangement of the converter unit 11. Thisis associated with the electrical drive machine 4 in another region ofits external circumference on the housing 12. When viewed in theinstalled position in the vehicle, it is preferably arranged in front ofor behind the electrical machine 4, in a side view. A configuration suchas this is shown in FIG. 2b.

[0046] Another arrangement option, which is not shown here, for thebraking resistor unit and/or the converter unit 11 if the electricaldrive machine 4 and the transmission unit 5 have considerably differentdimensions in the radial direction is to arrange them on the end face,which faces the transmission unit, above the transmission unit. However,in one particularly advantageous refinement, the converter unit 11 andthe electrical machine 4 form a physical unit. There are a wide range ofoptions for the design configuration of the combination of theelectrical machine 4 and the converter unit 11 to form a physical unit20. In particular, the specific configuration of the electrical couplingand of any additional mechanical coupling between the converter unit 11and the electrical machine 4 are within the knowledge of a personskilled in the art in this case and are carried out depending on theapplication and the characteristics of the standardized elements thatare used. The unit 20 is in this case provided at least by theelectrical coupling between the converter unit 11 and the electricalmachine 4. For this purpose, the electrical machine has four connections21, which are not shown in detail here but which, when coupled, areoperatively connected to respectively complementary connections on theconverter unit 11 associated with them. In a corresponding way to thearrangement of the converter unit 11 on the electrical machine 4, it ispossible to fix the converter unit 11 on the electrical machine 4 justby the means for providing the electrical coupling between the converterunit 11 and the electrical machine 4. The means for electrical coupling,which comprise mutually complementary connection elements, then at thesame time form the means for the mechanical connection between theconverter unit 11 and the electrical machine 4. Furthermore,configurations which are not described in detail here are feasible, inwhich means are provided for additional mechanical coupling between theconverter unit 11 and the electrical machine 4. In the simplest case,this is provided by an additional attachment of the converter unit 11,for example of the housing 22 of the converter unit, to the electricalmachine 4. The specific configuration of the coupling is in this casewithin the knowledge of a person skilled in the art and, in detail,depends on the converter units provided for that application, inparticular their dimensions and weight and the arrangement on theassociated electrical equipment.

[0047] The solution according to the invention can be used particularlyadvantageously in a shaft drive configuration for use in vehicles, inparticular passenger vehicles, with the electrical machine 4 preferablybeing in the form of a transverse flux machine, that is to say analternating current machine with transverse flux guidance.  1 Shaftdrive unit  2 Electrical drive unit for driving a wheel shaft with atransverse shaft structure  3, 3.1, 3.2 Wheel shaft  4 Electricalmachine which acts as a drive machine in the traction mode  5Transmission unit  6 Rotor  7 Stator  8 Input to the transmission unit 9.1, 9.2 Output from the transmission unit 10 Braking resistor unit 11Converter unit 12 Housing 13 End surface 14 External circumference 15Physical unit 16 External circumference of the wheel shaft 17 Part,enclosing the wheel shaft, on the housing 12 20 Unit 21 Connections 22Connecting elements 23 Epicyclic gear stage 24 Output 25 Differential26.1, 26.2 Output, differential 27 Input, differential 28 Input oroutput drive shaft of the electrical machine

1. A shaft drive unit (1), in particular an electrical drive unit (2)for driving a wheel shaft (3) for use in vehicles; 1.1 having anelectrical machine (4) comprising a rotor (6) and a stator (7); 1.2having a transmission unit (5), comprising at least one input (8) whichcan be connected in a rotationally fixed manner to the rotor (6) of theelectrical machine (4), and at least one output (9.1, 9.2) which can beconnected in a rotationally fixed manner to the wheel shaft (3); 1.3 theelectrical machine (4), the input (8) and the output (9.1, 9.2) of thetransmission unit (5) and the wheel shaft (3) being arranged coaxiallywith respect to one another; and 1.4 the electrical machine (4) havingat least one associated converter unit (11) and one associated brakingresistor unit (10); distinguished by the following features: 1.5 theconverter unit (11) is combined with the electrical machine (4) to forma physical unit (20); 1.6 the braking resistor unit (10) is arranged inthe immediate physical vicinity of the electrical machine (4) and aroundthe circumference of the input or output drive shaft (28) of theelectrical machine (4) or of the wheel shaft (3).
 2. The shaft drive (1)as claimed in claim 1, wherein means are provided for mechanicalconnection of the converter unit (11) to the electrical machine (4). 3.The shaft drive unit (1) as claimed in claim 2, wherein means are formedfor electrical coupling of the converter unit (11) to the electricalmachine (4), and means are formed for mechanical coupling of the samecomponents.
 4. The shaft drive unit (1) as claimed in one of claims 1 to3, wherein the convertor unit (11) is arranged on the externalcircumference (14) of the housing (12) of the electrical drive machine(4).
 5. The shaft drive unit (1) as claimed in one of claims 1 to 4,wherein the converter unit (11) is arranged in the housing of theelectrical drive machine (4).
 6. The shaft drive unit (1) as claimed inone of claims 1 to 3, wherein the converter unit (11) is arranged on oneend surface (13) of the electrical drive machine (4).
 7. The shaft driveunit (1) as claimed in one of claims 2 to 6, wherein the means formechanical coupling between the electrical machine (4) and the converterunit (11) associated with it comprise connection means (21, 22) whoseelements (4, 11) which are to be connected to one another are designedto be mutually complementary and to allow a force-fitting connection. 8.The shaft drive unit (1) as claimed in one of claims 2 to 6, wherein themeans for mechanical coupling between the electrical machine (4) and theconverter unit (11) associated with it comprise connection means (21,22) which are designed to be mutually complementary and allow aninterlocking connection.
 9. The shaft drive unit (1) as claimed in oneof claims 1 to 8, distinguished by the following features: 9.1 a largenumber of braking resistor units (10.1, 10.2, 10.3) are provided; 9.2the braking resistor units (10.1, 10.2, 10.3, 10.4, 10.5) are grouped,in one view, onto the wheel shaft (3) in the axial direction in a planein an annular shape around the circumference of the input or outputdrive shaft (28) of the electrical machine (4) or of the wheel shaft(3).
 10. The shaft drive unit (1) as claimed in one of claims 1 to 9,wherein each braking resistor unit (10.1, 10.2, 10.3) has a geometricalstructure which, in the circumferential direction of the input or outputdrive shaft (28) of the electrical machine (4) or of the wheel shaft(3), at least partially encloses said input or output drive shaft (28).11. The shaft drive unit (1) as claimed in claim 10, wherein the brakingresistor unit (10.1, 10.2, 10.3) is designed in an annular shape. 12.The shaft drive unit (1) as claimed in claim 11, distinguished by thefollowing features: 12.1 a large number of braking resistor units (10.1,10.2, 10.3) are provided, and are arranged alongside one another; 12.2the braking resistor units (10.1, 10.2, 10.3) are of modularconstruction, and can be mechanically and electrically coupled to oneanother.
 13. The shaft drive unit (1) as claimed in one of claims 1 to12, wherein the electrical machine (4) is in the form of a transverseflux machine.
 14. A drive system 14.1 having a shaft drive unit (1) asclaimed in one of claims 1 to 13; 14.2 having a power supply system forthe shaft drive unit 14.3 the power supply system comprising a fuel cellwhich is electrically connected to the electrical machine.
 15. A drivesystem 15.1 having a shaft drive unit (1) as claimed in one of claims 1to 13; 15.2 having a power supply system for the shaft drive unit (1);15.2 the power supply system comprising an internal combustion engine,an electrical machine which can be mechanically coupled to it and can beoperated as a generator in the traction mode, and an electrical couplingfor connecting the power supply system to the electrical machine (4) forthe shaft drive (1).